Method of preparing a packaged antimicrobial medical device

ABSTRACT

A method of making a packaged antimicrobial suture comprising the steps of providing a containment compartment that is substantially free of an antimicrobial agent; positioning a suture within the containment compartment, said suture comprising one or more surfaces having an antimicrobial agent disposed thereon, said antimicrobial agent being selected from the group consisting of halogenated hydroxyl ethers, acyloxydiphenyl ethers, and combinations thereof; placing the containment compartment having the suture in an outer package; and subjecting the outer package, the containment compartment and the suture to time, temperature and pressure conditions sufficient to transfer an effective amount of the antimicrobial agent from the suture to the containment compartment, while retaining an effective amount of said antimicrobial agent on the suture, thereby substantially inhibiting bacterial colonization on the suture and the containment compartment.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a continuation of U.S. Ser. No. 12/417,518, filed onApr. 4, 2009, which is a continuation of U.S. Ser. No. 11/301,365, filedon Dec. 13, 2005, which is a continuation-in-part of U.S. Ser. No.10/808,669, filed on Mar. 25, 2004, which is a continuation-in-part ofU.S. Ser. No. 10/603,317 filed on Jun. 25, 2003, which is acontinuation-in-part of U.S. Ser. No. 10/367,497 filed on Feb. 15, 2003,which claimed the benefit of U.S. Provisional Application No. 60/416,114filed on Oct. 4, 2002, the contents of each are hereby incorporated byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a packaged antimicrobial medical deviceand its methods of making.

BACKGROUND OF THE INVENTION

Each year, patients undergo a vast number of surgical procedures in theUnited States. Current data shows about twenty-seven million proceduresare performed per year. Post-operative or surgical site infections(“SSIs”) occur in approximately two to three percent of all cases. Thisamounts to more than 675,000 SSIs each year.

The occurrence of SSIs is often associated with bacteria that cancolonize on implantable medical devices used in surgery. During asurgical procedure, bacteria from the surrounding atmosphere may enterthe surgical site and attach to the medical device. Specifically,bacteria can spread by using the implanted medical device as a pathwayto surrounding tissue. Such bacterial colonization on the medical devicemay lead to infection and trauma to the patient. Accordingly, SSIs maysignificantly increase the cost of treatment to patients.

Implantable medical devices that contain antimicrobial agents applied toor incorporated within have been disclosed and/or exemplified in theart. Examples of such devices are disclosed in European PatentApplication No. EP 0 761 243. Actual devices exemplified in theapplication include French Percuflex catheters. The catheters weredip-coated in a coating bath containing2,4,4′-tricloro-2-hydroxydiphenyl ether (Ciba Geigy Irgasan (DP300)) andother additives. The catheters then were sterilized with ethylene oxideand stored for thirty days. Catheters coated with such solutionsexhibited antimicrobial properties, i.e., they produced a zone ofinhibition when placed in a growth medium and challenged withmicroorganism, for thirty days after being coated. It is not apparentfrom the application at what temperature the sterilized, coatedcatheters were stored.

Most implantable medical devices are manufactured, sterilized andcontained in packages until opened for use in a surgical procedure.During surgery, the opened package containing the medical device,packaging components contained therein, and the medical device, areexposed to the operating room atmosphere, where bacteria from the airmay be introduced. Incorporating antimicrobial properties into thepackage and/or the packaging components contained therein substantiallyprevents bacterial colonization on the package and components once thepackage has been opened. The antimicrobial package and/or packagingcomponents in combination with the incorporation of antimicrobialproperties onto the medical device itself would substantially ensure anantimicrobial environment about the sterilized medical device.

SUMMARY OF THE INVENTION

The present invention relates to packaged antimicrobial medical devicesand methods for preparing such packaged medical devices. In accordancewith embodiments of the present invention, an antimicrobial agent isdisposed on the surfaces of the medical device. The medical device ispositioned within a package or within a packaging component such as acontainment compartment within a package, and upon being subjected tosufficient conditions, a portion of the antimicrobial agent transfersfrom the medical device to the package and/or the containmentcompartment. The transfer of the antimicrobial agent is in an amountsufficient to inhibit bacterial growth on and about the medical device,the package and/or the containment compartment.

An embodiment of the packaged antimicrobial medical device includes atleast one package having an inner surface with an antimicrobial agentdisposed thereon, the antimicrobial agent being selected fromhalogenated hydroxyl ethers, acyloxydiphenyl ethers, and combinationsthereof, in an amount sufficient to substantially inhibit bacterialcolonization on the package; and at least one medical device positionedwithin the package, the medical device having one or more surfaceshaving an antimicrobial agent disposed thereon, the antimicrobial agentbeing selected from halogenated hydroxyl ethers, acyloxydiphenyl ethers,and combinations thereof, in an amount sufficient to substantiallyinhibit bacterial colonization on the medical device.

Another embodiment of the packaged antimicrobial medical device includesa package having an inner surface and a containment compartment forsecuring the medical device and that resides within the package. In thisembodiment, at least one surface of the containment compartment includesan antimicrobial agent disposed thereon, present in an amount sufficientto substantially inhibit bacterial colonization on the containmentcompartment. In an alternate embodiment, the inner surface of thepackage and at least one surface of the containment compartment includean antimicrobial agent disposed thereon, present in an amount sufficientto substantially inhibit bacterial colonization on the package and thecontainment compartment. The packaged medical device also includes atleast one medical device positioned within the containment compartment.The medical device also has one or more surfaces having an antimicrobialagent disposed thereon. The antimicrobial agent is present on themedical device in an amount sufficient to substantially inhibitbacterial colonization on the medical device. The antimicrobial agentdisposed on the package, the containment compartment and medical devicemay be selected from antimicrobial compounds which include halogenatedhydroxyl ethers, acyloxydiphenyl ethers, and combinations thereof.

Another embodiment is an antimicrobial suture assembly comprising acontainment compartment comprising one or more surfaces having anantimicrobial agent disposed thereon, the antimicrobial agent beingselected from the group consisting of halogenated hydroxyl ethers,acyloxydiphenyl ethers, and combinations thereof, in an amountsufficient to substantially inhibit bacterial colonization on thecontainment compartment; and a suture positioned within the containmentcompartment, the suture comprising one or more surfaces having anantimicrobial agent disposed thereon, the antimicrobial agent beingselected from the group consisting of halogenated hydroxyl ethers,acyloxydiphenyl ethers, and combinations thereof, in an amountsufficient to substantially inhibit bacterial colonization on thesuture.

The present invention is also directed to a method for preparing apackaged antimicrobial medical device, which includes the steps ofproviding a package and/or a containment compartment that issubstantially free of an antimicrobial agent; positioning a medicaldevice within the package or the containment compartment, the medicaldevice including one or more surfaces having an antimicrobial agentdisposed thereon, the antimicrobial agent being selected from the groupconsisting of halogenated hydroxyl ethers, acyloxydiphenyl ethers, andcombinations thereof; subjecting the package and/or the containmentcompartment and the medical device to conditions sufficient to transfera first portion of the antimicrobial agent from the medical device tothe package and/or the containment compartment, while retaining a secondportion of the antimicrobial agent on the surface of the medical device,thereby substantially inhibiting bacterial colonization on the medicaldevice, the package and/or the containment compartment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph illustrating the transfer of an antimicrobial agentfrom the medical device to a containment compartment at 55 C as afunction of time.

FIG. 2 is a photographic representation of a containment compartment ona TSA plate challenged Staphylococcus aureus.

FIG. 3 is a photographic representation of a suture on a TSA platechallenged Staphylococcus epidermidis.

FIG. 4 is a scanning electron microscope (“SEM”) image of suture strandscoated with an antimicrobial composition and exposed tomethicillin-resistant Staphylococcus epidermidis.

FIG. 5 is a scanning electron microscope (“SEM”) image of suturestrands, which are not coated with an antimicrobial composition, exposedto methicillin-resistant Staphylococcus epidermidis.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION PackagedAntimicrobial Medical Device

One embodiment of the packaged antimicrobial medical device includes atleast one package having an inner surface. The inner surface includes anantimicrobial agent disposed thereon, present in an amount sufficient tosubstantially inhibit bacterial colonization on the package. Thepackaged medical device also includes at least one medical devicepositioned within the package. The medical device also has one or moresurfaces having an antimicrobial agent disposed thereon. Theantimicrobial agent is present on the medical device, in an amountsufficient to substantially inhibit bacterial colonization on themedical device. The antimicrobial agent disposed on the package andmedical device may be selected from antimicrobial compounds whichinclude halogenated hydroxyl ethers, acyloxydiphenyl ethers, andcombinations thereof.

In another embodiment, the packaged medical device includes a packagehaving an inner surface and a containment compartment for securing themedical device and that resides within the package. In this embodiment,at least one surface of the containment compartment includes anantimicrobial agent disposed thereon, present in an amount sufficient tosubstantially inhibit bacterial colonization on the containmentcompartment. In an alternate embodiment, the inner surface of thepackage and at least one surface of the containment compartment includean antimicrobial agent disposed thereon, present in an amount sufficientto substantially inhibit bacterial colonization on the package and thecontainment compartment. The packaged medical device also includes atleast one medical device positioned within the containment compartment.The medical device also has one or more surfaces having an antimicrobialagent disposed thereon. The antimicrobial agent is present on themedical device, in an amount sufficient to substantially inhibitbacterial colonization on the medical device. The antimicrobial agentdisposed on the package, the containment compartment and medical devicemay be selected from antimicrobial compounds which include halogenatedhydroxyl ethers, acyloxydiphenyl ethers, and combinations thereof.

Another embodiment is an antimicrobial suture assembly comprising acontainment compartment comprising one or more surfaces having anantimicrobial agent disposed thereon, the antimicrobial agent beingselected from the group consisting of halogenated hydroxyl ethers,acyloxydiphenyl ethers, and combinations thereof, in an amountsufficient to substantially inhibit bacterial colonization on thecontainment compartment; and a suture positioned within the containmentcompartment, the suture comprising one or more surfaces having anantimicrobial agent disposed thereon, the antimicrobial agent beingselected from the group consisting of halogenated hydroxyl ethers,acyloxydiphenyl ethers, and combinations thereof, in an amountsufficient to substantially inhibit bacterial colonization on thesuture.

The medical devices described herein are generally implantable medicaldevices, including but not limited to mono and multifilament sutures,surgical meshes such as hernia repair mesh, hernia plugs, brachy seedspacers, suture clips, suture anchors, adhesion prevention meshes andfilms, and suture knot clips. Also included are implantable medicaldevices that are absorbable and non-absorbable. An absorbable polymer isdefined as a polymer that, when exposed to physiological conditions,will degrade and be absorbed by the body over a period of time.Absorbable medical devices typically are formed from generally known,conventional absorbable polymers including, but not limited to,glycolide, lactide, co-polymers of glycolide, or mixtures of polymers,such as polydioxanone, polycaprolactone and equivalents thereof.Preferably, the polymers include polymeric materials selected from thegroup consisting of greater than about 70% polymerized glycolide,greater than about 70% polymerized lactide, polymerized1,4-dioxan-2-one, greater than about 70% polypeptide, copolymers ofglycolide and lactide, greater than about 70% cellulosics and cellulosicderivatives.

Examples of absorbable medical device include mono and multifilamentsutures. The multifilament suture includes sutures wherein a pluralityof filaments are formed into a braided structure. Examples ofnon-absorbable medical devices include mono and multifilament sutures,surgical meshes such as hernia repair mesh, hernia plugs and brachy seedspacers, which may be polymeric or nonpolymeric.

Suitable antimicrobial agents may be selected from, but are not limitedto, halogenated hydroxyl ethers, acyloxydiphenyl ethers, or combinationsthereof. In particular, the antimicrobial agent may be a halogenated2-hydroxy diphenyl ether and/or a halogenated 2-acyloxy diphenyl ether,as described in U.S. Pat. No. 3,629,477, and represented by thefollowing formula:

In the above formula, each Hal represents identical or different halogenatoms, Z represents hydrogen or an acyl group, and w represents apositive whole number ranging from 1 to 5, and each of the benzenerings, but preferably ring A can also contain one or several lower alkylgroups which may be halogenated, a lower alkoxy group, the allyl group,the cyano group, the amino group, or lower alkanoyl group. Preferably,methyl or methoxy groups are among the useful lower alkyl and loweralkoxy groups, respectively, as substituents in the benzene rings. Ahalogenated lower alkyl group, trifluoromethyl group is preferred.

Antimicrobial activity similar to that of the halogen-o-hydroxy-diphenylethers of the above formula is also attained using the O-acylderivatives thereof which partially or completely hydrolyze under theconditions for use in practice. The esters of acetic acid, chloroaceticacid, methyl or dimethyl carbamic acid, benzoic acid, chlorobenzoicacid, methylsulfonic acid and chloromethylsulfonic acid are particularlysuitable.

One particularly preferred antimicrobial agent within the scope of theabove formula is 2,4,4′-trichloro-2′-hydroxydiphenyl ether, commonlyreferred to as triclosan (manufactured by Ciba Geigy under the tradename Irgasan DP300 or Irgacare MP). Triclosan is a broad-spectrumantimicrobial agent that has been used in a variety of products, and iseffective against a number of organisms commonly associated with SSIs.Such microorganisms include, but are not limited to, genusStaphylococcus, Staphylococcus epidermidis, Staphylococcus aureus,methicillin-resistant Staphylococcus epidermidis, methicillin-resistantStaphylococcus aureus, and combinations thereof.

In addition to the antimicrobial agents described above, the medicaldevice optionally may have a biocide, a disinfectant and/or anantiseptic, including but not limited to alcohols such as ethanol andisopropanol; aldehydes such as glutaraldehyde and formaldehyde; anilidessuch as triclorocarbanilide; biguanides such as chlorhexidine;

chlorine-releasing agents such as sodium hypochlorite, chlorine dioxideand acidified sodium chlorite; iodine-releasing agents such aspovidone-iodine and poloxamer-iodine; metals such as silver nitrate,silver sulfadiazine, other silver agents, copper-8-quinolate and bismuththiols; peroxygen compounds such as hydrogen peroxide and peraceticacid; phenols; quaternary ammonium compounds such as benzalkoniumchloride, cetrimide and ionenes-polyquaternary ammonium compounds. Themedical device optionally may have antibiotics, including but notlimited to penicillins such as amoxicillin, oxacillin and piperacillin;cephalosporins parenteral such as cefazolin, cefadroxil, cefoxitin,cefprozil, cefotaxime and cefdinir; monobactams such as aztreonam;beta-lactamase inhibitors such as clavulanic acid sulbactam;glycopeptide such as vancomycin; polymixin; quinolones such as nalidixicacid, ciprofloxacin and levaquin; metranidazole; novobiocin;actinomycin; rifampin; aminoglycosides such as neomycin and gentamicin;tetracyclines such as doxycycline; chloramphenicol; macrolide such aserythromycin; clindamycin; sulfonamide such as sulfadiazine;trimethoprim; topical antibiotics; bacitracin; gramicidin; mupirocin;and/or fusidic acid. Optionally, the medical device may haveantimicrobial peptides such as defensins, magainin and nisin; lyticbacteriophage; surfactants; adhesion blockers such as antibodies,oligosaccharides and glycolipids; oligonucleotides such as antisenseRNA; efflux pump inhibitors; photosensitive dyes such as porphyrins;immune modulators such as growth factors, interleukins, interferons andsynthetic antigens; and/or chelators such as EDTA, sodiumhexametaphosphate, lactoferrin and transferrin.

It is advantageous to use a coating composition as a vehicle fordelivering the antimicrobial agent to the surface of the device wheresuch coating already is used conventionally in the manufacture of thedevice, such as, for example, absorbable and non-absorbablemultifilament sutures. Examples of medical devices, as well as coatingsthat may be applied thereto, may be found in U.S. Pat. Nos. 4,201,216,4,027,676, 4,105,034, 4,126,221, 4,185,637, 3,839,297, 6,260,699,5,230,424, 5,555,976, 5,868,244, and 5,972,008, each of which is herebyincorporated herein in its entirety. As disclosed in U.S. Pat. No.4,201,216, the coating composition may include a film-forming polymerand a substantially water-insoluble salt of a C₆ or higher fatty acid.As another example, an absorbable coating composition that may be usedfor an absorbable medical device may include poly(alkylene oxylates)wherein the alkylene moieties are derived from C₆ or mixtures of C₄ toC₁₂ diols, which is applied to a medical device from a solvent solution,as disclosed in U.S. Pat. No. 4,105,034. The coating compositions of thepresent invention may include a polymer or co-polymer, which may includelactide and glycolide, as a binding agent. The compositions may alsoinclude calcium stearate, as a lubricant, and an antimicrobial agent.Medical devices not conventionally employing a coating in themanufacturing process, however, also may be coated with a compositioncomprising an antimicrobial agent. The coating may be applied to thedevice by, for example, dip coating, spray coating, suspended dropcoating, or any other conventional coating means.

Absorbable medical devices are moisture sensitive, that is, they aredevices that will degrade if exposed to moisture in the atmosphere or inthe body. It is known by those of ordinary skill in the art that medicaldevices made from absorbable polymers may deteriorate and lose theirstrength if they come into contact with water vapor prior to use duringsurgery. For instance, the desirable property of in vivo tensilestrength retention for sutures will be rapidly lost if the sutures areexposed to moisture for any significant period of time prior to use.Therefore, it is desirable to use a hermetically sealed package forabsorbable medical devices. A hermetically sealed package is definedherein to mean a package made of a material that serves as both asterile barrier and a gas barrier, i.e., prevents or substantiallyinhibits moisture and gas permeation.

Materials useful for constructing the package for absorbable medicaldevices, for example, include single and multilayered conventional metalfoil products, often referred to as heat-sealable foils. These types offoil products are disclosed in U.S. Pat. No. 3,815,315, which is herebyincorporated by reference in its entirety. Another type of foil productthat may be utilized is a foil laminate referred to in the field of artas a peelable foil. Examples of such peelable foil and substrates aredisclosed in U.S. Pat. No. 5,623,810, which is hereby incorporated byreference in its entirety. If desired, conventional non-metallic polymerfilms in addition to or in lieu of metal foil may be used to form thepackage for absorbable medical devices. Such films are polymeric and mayinclude conventional polyolefins, polyesters, acrylics and the like,combinations thereof and laminates. These polymeric films substantiallyinhibit moisture and oxygen permeation and may be coated withconventional coatings, such as, for example, mineral coatings thatdecrease or reduce gas intrusion. The package may comprise a combinationof polymer and metal foils, particularly a multi-layerpolymer/metal-foil composite.

Nonabsorbable medical devices may be packaged in any of the materialsdescribed above. In addition, it is desirable to package nonabsorbablemedical devices in a package made of a material that serves as a sterilebarrier, such as a porous material, i.e., medical grade paper, or apolymeric film that is permeable to moisture and gas, i.e., TYVEK film,manufactured by DuPont and made from high-density polyethylene fibers.

Packages for surgical needles, sutures and combinations including thesuture and a surgical needle typically comprise a suture tray as thecontainment compartment, for securely holding the suture and/or surgicalneedle in place. One type of containment compartment typically used forsurgical needles and/or sutures is a folder package made from a stiff,medical grade paper. A folder package will typically have a plurality offoldable panels and cut-out tabs and tab pockets. Folder packages forsurgical needles and sutures are illustrated and disclosed in thefollowing patents, each of which is herby incorporated by reference inits entirety: U.S. Pat. Nos. 4,126,221, 4,120,395 and 5,555,976. Anotherconventionally used containment compartment for surgical needles and/orsutures is a molded plastic tray having a central floor surrounded by anouter winding channel for receiving and retaining a suture, e.g., anoval channel. The containment compartment may further include a medicalgrade paper or plastic cover that may be mounted to the top of thewinding channel, or the molded plastic tray may have molded retainerelements, in order to maintain the suture in the channel. The moldedplastic tray may be made from a thermoplastic material selected from thegroup consisting of polyester, polyvinyl chloride, polypropylene,polystyrene, and polyethylene. Containment compartments having windingchannels are illustrated in the following, each of which is herebyincorporated by reference in its entirety: U.S. Pat. Nos. 4,967,902,5,213,210 and 5,230,424.

Microorganisms of the genus Staphylococcus are the most prevalent of allof the organisms associated with device-related surgical site infection.S. aureus and S. epidermidis are commonly present on patients' skin andas such are introduced easily into wounds. One of the most efficaciousantimicrobial agents against Staphylococcus is2,4,4′-trichloro-2′-hydroxydiphenyl ether. This compound has a minimuminhibitory concentration (MIC) against S. aureus of 0.01 ppm, asmeasured in a suitable growth medium and as described by Bhargava, H. etal in the American Journal of Infection Control, June 1996, pages209-218. The MIC for a particular antimicrobial agent and a particularmicroorganism is defined as the minimum concentration of thatantimicrobial agent that must be present in an otherwise suitable growthmedium for that microorganism, in order to render the growth mediumunsuitable for that microorganism, i.e., the minimum concentration toinhibit growth of that microorganism. The phrase “an amount sufficientto substantially inhibit bacterial colonization” as used herein isdefined as the minimum inhibitory concentration for S. aureus orgreater.

A demonstration of this MIC is seen in the disk diffusion method ofsusceptibility. A filter paper disk, or other object, impregnated with aparticular antimicrobial agent is applied to an agar medium that isinoculated with the test organism. Where the anti-microbial agentdiffuses through the medium, and as long as the concentration of theantimicrobial agent is above the minimum inhibitory concentration (MIC),none of the susceptible organism will grow on or around the disk forsome distance. This distance is called a zone of inhibition. Assumingthe antimicrobial agent has a diffusion rate in the medium, the presenceof a zone of inhibition around a disk impregnated with an antimicrobialagent indicates that the organism is inhibited by the presence of theantimicrobial agent in the otherwise satisfactory growth medium. Thediameter of the zone of inhibition is inversely proportional to the MIC.

Alternatively, the concentration of triclosan on the surface of amedical device such as a coated suture may be greater than about 0.01ppm (wt./wt. coating) or between about 30 ppm to 5,000 ppm (wt./wt.suture). The concentration of triclosan on the surface of package orcontainment compartment may be between about 5 ppm to 5,000 ppm (wt./wt.package or compartment). For other particular applications, however,higher amounts of antimicrobial agent may be useful and should beconsidered well within the scope of the present invention.

Method for Making a Packaged Antimicrobial Medical Device

In accordance with various methods of the present invention, a packageand containment compartment that are initially substantially free of anantimicrobial agent, i.e., no antimicrobial agent is intended to bepresent on the package or containment compartment surfaces, may beprovided. A medical device, which has an antimicrobial agent disposedthereon, is positioned within the package or containment compartment.Subsequently, the package, the containment compartment if utilized andthe medical device are subjected to time, temperature and pressureconditions sufficient to vapor transfer a portion of the antimicrobialagent from the medical device to the package and/or the containmentcompartment.

The rate of transfer of an antimicrobial agent such as triclosan fromthe medical device to the package and/or containment compartment issubstantially dependent upon the time, temperature and pressureconditions under which the package with the containment compartment andthe medical device is processed, stored and handled. For example, FIG. 1illustrates that triclosan is capable of transferring from a suture to acontainment compartment (in a closed vial at atmospheric pressure) whenthe temperature is maintained at 55 C over a period of time. Theconditions to effectively vapor transfer an antimicrobial agent such astriclosan include a closed environment, atmospheric pressure, atemperature of greater than 40 C, for a period of time ranging from 4 to8 hours. Also included are any combinations of pressure and temperatureto render a partial pressure for the antimicrobial agent that is thesame as the partial pressure rendered under the conditions describedabove, in combination with a period of time sufficient to render aneffective amount or concentration of the antimicrobial agent on thepackage and/or containment compartment, i.e., the minimum inhibitoryconcentration (MIC) or greater. Specifically, it is known to one ofordinary skill that if the pressure is reduced, the temperature may bereduced to effect the same partial pressure. Alternatively, if thepressure is reduced, and the temperature is held constant, the timerequired to render an effective amount or concentration of theantimicrobial agent on the package and/or containment compartment may beshortened. While a portion of the antimicrobial agent is transferred tothe package and/or containment compartment during this process, a secondportion is retained on the surface of the medical device. Accordingly,after the transfer, the medical device and the package and/or thecontainment compartment contain the antimicrobial agent in an amounteffective to substantially inhibit bacterial colonization thereon andthereabout.

Medical devices typically are sterilized to render microorganismslocated thereon non-viable. In particular, sterile is understood in thefield of art to mean a minimum sterility assurance level of 10⁻⁶.Examples of sterilization processes are described in U.S. Pat. Nos.3,815,315, 3,068,864, 3,767,362, 5,464,580, 5,128,101 and 5,868,244,each of which is incorporated herein in its entirety. Specifically,absorbable medical devices may be sensitive to radiation and heat.Accordingly, it may be desirable to sterilize such devices usingconventional sterilant gases or agents, such as, for example, ethyleneoxide gas.

An ethylene oxide sterilization process is described below, since thetime, temperature and pressure conditions sufficient to vapor transfer aportion of the antimicrobial agent from the medical device to thepackage and/or containment compartment, are present in an ethylene oxidesterilization process. However the time, temperature and pressureconditions sufficient to vapor transfer the antimicrobial agent from themedical device to the package and/or containment compartment may beeffected alone or in other types of sterilization processes, and are notlimited to an ethylene oxide sterilization process or to sterilizationprocesses in general.

As discussed above, absorbable medical devices are sensitive to moistureand are therefore often packaged in hermetically sealed packages, suchas sealed foil packages. However, sealed foil packages are alsoimpervious to sterilant gas. In order to compensate for this and utilizefoil packages in ethylene oxide gas sterilization processes, processeshave been developed using foil packages having gas permeable or perviousvents (e.g., TYVEK polymer). The gas permeable vents are mounted to anopen end of the package and allow the passage of air, water vapor andethylene oxide into the interior of the package. After the sterilizationprocess is complete, the package is sealed adjacent to the vent, and thevent is cut away or otherwise removed, thereby producing a gasimpervious hermetically sealed package. Another type of foil packagehaving a vent is a pouch-type package having a vent mounted adjacent toan end of the package, wherein the vent is sealed to one side of thepackage creating a vented section. After the sterilization process iscomplete the package is sealed adjacent to the vent, and the package iscut away for the vented section.

The package and containment compartment are substantially free of, andpreferably completely free of, antimicrobial agent prior to the transferof the antimicrobial agent from the medical device to the package and/orthe containment compartment. The medical device may first be placedwithin the containment compartment, if necessary, and then within thepackage. After the peripheral seal and side seals have been formed inthe package, the packaged medical device may be placed into aconventional ethylene oxide sterilization unit. If the package is a foilpackage, the gas permeable vents described above may be used. Prior tothe start of the cycle, the sterilization unit may be heated to aninternal temperature of about 25° C. The sterilization unit ismaintained about 22 to 37° C. throughout the humidification andsterilization cycles.

Next, a vacuum may be drawn on the sterilization unit to achieve avacuum of approximately 1.8 to 6.0 kPa. In a humidification cycle, steamthen may be injected to provide a source of water vapor for the productto be sterilized. The packaged medical devices may be exposed to watervapor in the sterilization unit for a period of time of about 60 to 90minutes. Times may vary, however, depending upon the medical devicebeing sterilized.

Following this humidification portion of the cycle, the sterilizationunit may be pressurized by the introduction of dry inert gas, such asnitrogen gas, to a pressure of between about 42 and 48 kPa. Once thedesired pressure is reached, pure ethylene oxide may be introduced intothe sterilization unit until the pressure reaches about 95 kPa. Theethylene oxide may be maintained for a period of time effective tosterilize the packaged medical device. For example, the ethylene oxidemay be maintained in the sterilization unit for about 360 to about 600minutes for surgical sutures. The time required to sterilize othermedical devices may vary depending upon the type of product and thepackaging. The ethylene oxide then may be evacuated from thesterilization unit and the unit may be maintained under vacuum at apressure of approximately 0.07 kPa for approximately 150 to 300 minutesin order to remove residual moisture and ethylene oxide from thesterilized packaged medical devices. The pressure in the sterilizationunit may be returned to atmospheric pressure.

The following stage of the process is a drying cycle. The packagedmedical device may be dried by exposure to dry nitrogen and vacuum overa number of cycles sufficient to effectively remove residual moistureand water vapor from the packaged medical device to a preselected level.During these cycles, the packaged medical device may be subjected to anumber of pressure increases and decreases, at temperatures greater thanroom temperature. Specifically, the jacket temperature of the dryingchamber may be maintained at a temperature of between approximately 53°C. to 57° C. throughout the drying cycle. Higher temperatures, however,may be employed, such as about 65° C. to 70° C. for sutures, and higherdepending upon the medical device being sterilized. A typical dryingcycle includes the steps of increasing the pressure with nitrogen toapproximately 100 kPa, evacuating the chamber to a pressure ofapproximately 0.07 kPa over a period of 180 to 240 minutes,reintroducing nitrogen to a pressure of 100 kPa and circulating thenitrogen for approximately 90 minutes, evacuating the chamber to apressure of approximately 0.01 kPa over a period of approximately 240 to360 minutes and maintaining a pressure of not more than 0.005 kPa for anadditional 4 to 96 hours. At the end of the humidification,sterilization and drying cycles, which takes typically about 24 hours,the vessel is returned to ambient pressure with dry nitrogen gas. Oncedrying to the preselected moisture level is complete, the packagedmedical device may be removed from the drying chamber and stored in ahumidity controlled storage area.

Upon completion of the sterilization process, the antimicrobial medicaldevice, the package and/or the containment compartment have thereon anamount of the antimicrobial agent effective to substantially inhibitcolonization of bacteria on or adjacent the antimicrobial device, thepackage and/or the containment compartment.

EXAMPLE 1

A series of USP standard size 5-0 coated polyglactin 910 sutures werecoated with a 2% triclosan coating composition so that each suturecontained about a total of 23.2 μg triclosan before sterilization. Thecoated sutures each were placed in a package as described herein aboveincluding a containment component, i.e., a tray, for holding the sutureand a paper component for covering the suture in the tray. The suture inthe containment component and packaging were sterilized as describedherein above. After sterilization, it was determined that that suturecontained about 5.5 μg triclosan, the tray about 0.2 μg triclosan, thepaper component about 2.3 μg triclosan, and the package heat sealcoating about 1.5 μg triclosan. Triclosan not recovered aftersterilization was about 13.7 μg triclosan. FIG. 1 indicates triclosantransfer from the antimicrobial suture to the tray of the package as afunction of time at 55° C.

After sterilization, the paper component and tray of the sterilizedpackage were tested for antimicrobial properties utilizing a zone ofinhibition test as indicated herein below. Zone of inhibition testing isa conventional method for estimating the inhibitory effects ofantimicrobial substances against specific bacterial strains of interest.Zone of inhibition assays are useful for testing diffusible agents. Asthe agent diffuses away from the disk, the concentration decreaseslogarithmically. The sensitivity of the organism to the agent is judgedby the appearance and size of a zone where no growth occurs, i.e., thezone of inhibition.

A comparative example of a package that contained a conventionalcommercially available suture, i.e., not having triclosan appliedthereto, also was prepared and tested for antimicrobial properties.

FIG. 2 is a photographic representation of the zone of inhibition withrespect to a tray of the antimicrobial package on a TSA plate challengedwith Staphylococcus aureus.

The results of the zone of inhibition assays for the paper component andtray are listed in Table 1. The zones were measured for both treated anduntreated tray and paper component. As shown in Table 1, zones ofinhibition were present for all treated components against bothStaphylococcus aureus and Staphylococcus epidermidis. The untreatedcomponents exhibited no zones of inhibition.

TABLE 1 Zone of Inhibition Assay for Package Components Treated PackageUntreated Package Component Zone size Component Zone size Staphylococcusepidermidis Tray 18 mm Tray 0 Paper 13 mm Paper 0 Staphylococcus aureusTray 12 mm Tray 0 Paper 13 mm Paper 0

EXAMPLE 2

This example is a 24-hour aqueous immersion assay. The purpose of thisassay was to determine the effect of aqueous exposure on theantimicrobial properties of suture material for a range of suturediameters. Sterile sutures in USP sizes 2-0, 3-0, 4-0, and 5-0, with andwithout a 1% triclosan coating applied thereto, were aseptically cutinto 5-cm pieces. One half of the cut pieces were stored in a sterilePetri dish and kept under a dry nitrogen atmosphere for 24 hours (drysuture). One half of the cut pieces were aseptically transferred tosterile 0.85% saline and incubated at 37° C. for 24 hours (wet sutures).

The dry and wet sutures were then aseptically placed in individualsterile Petri dishes and challenged with 100 microliters of inoculumcontaining 10⁵ colony-forming units (CFU) of Staphylococcus aureus orStaphylococcus epidermidis. Ten replicates of each suture size were usedfor each organism and for both the dry and wet sample groups. TSA waspoured into each dish and allowed to solidify. The plates were incubatedat 37° C. for 48 hours. After incubation, the plates were examined undera darkfield colony counter and the zones of inhibition were measured.

The results of the zone of inhibition assays are listed in Table 2.Zones of inhibition were present for all sizes of coated polyglactin 910suture having triclosan applied thereto. Both the dry and wet samplesexhibited significant zones of inhibition. The coated polyglactin 910suture controls had no zones of inhibition. A typical zone of inhibitionis depicted in FIG. 3.

TABLE 2 24 Hour Aqueous Immersion Assay: Zone of Inhibition DiameterZone Diameter Average (mm) Suture S aureus S epidermidis Material DryWet Dry Wet Size 2-0 +Triclosan 10 9 10 9 Control 0 0 0 0 Size 3-0+Triclosan 10 10 10 8 Control 0 0 0 0 Size 4-0 +Triclosan 10 3 10 2Control 0 0 0 0 Size 5-0 +Triclosan 10 3 10 2 Control 0 0 0 0

All suture samples were from different lots. Average zone diameter isbased on triplicate plates.

As shown in FIG. 3, areas of inhibited bacterial growth were observedaround coated polyglactin 910 suture containing triclosan, while thecontrol suture without triclosan had confluent bacterial growth. Theresponse was similar for Staphylococcus epidermidis (shown),Staphylococcus aureus, MRSA, and MRSE, and was consistent for a varietyof suture sizes.

EXAMPLE 4

This example is directed to a 7-day aqueous immersion assay. The purposeof this assay was to determine if the antimicrobial effect of triclosantreatment would endure for 7 days in a buffered aqueous environment.

Sterile USP size 2-0 coated polyglactin 910 suture coated with a 1%, 2%,and 3% triclosan coating solution, respectively, and ethylene oxidesterilized USP size 2-0 coated polyglactin suture were aseptically cutinto 5-cm pieces. Samples were tested on each of 7 days in triplicate.

On day 1, 3 pieces of each suture material were placed into individualsterile Petri dishes and inoculated with 0.1 mL of challenge organismcontaining approximately 10⁴ CFU. TSA was poured into each dish andallowed to solidify. All remaining pieces of suture material were placedinto 100 mL of sterile phosphate buffered 0.85% saline (PBS). Every 24hours for the next 6 days, 3 pieces of each suture material were removedfrom the PBS, inoculated, and pour plated in tryptic/soy/agar (TSA). Allplates were incubated at 37° C. for 48 hours and the plates examined forthe presence or absence of a zone of inhibition.

The results for the 7-day assay are presented in Table 4. The coatedpolyglactin 910 suture with triclosan produced zones of inhibition afterevery challenge. The control coated polyglactin 910 suture withouttriclosan produced no growth inhibition.

TABLE 4 7-Day Aqueous Immersion Assay: Zone of Inhibition Diameter ZoneDiameter Average (mm) Triclosan Day coating 1 2 3 4 5 6 7 1% 20 18 20 2019 21 20 2% 24 20 22 21 24 24 23 3% 27 25 15 25 27 30 27 Control (0%) 00 0 0 0 0 0

All suture samples were from different lots. Average diameter is basedon triplicate plates. This example is a demonstration of the efficacy ofthe antimicrobial suture where samples of the antimicrobial suture and aconventional suture were each separately exposed by immersion in aqueousbuffer as a model of physiological conditions for up to seven days. Oneach day, samples of both the conventional and the antimicrobial sutureof the invention were removed and placed on tryptic/soy/agar (TSA)plates that had been inoculated with a 10⁴ colony forming unit (CFU)

Staphylococcus challenge. As is shown in Table 4, the antimicrobialsuture of the invention developed a zone of inhibition around it on theplate, even after seven days of immersion, providing evidence that theconcentration of the antimicrobial agent on and around the antimicrobialsuture of the invention was still above the MIC, while the conventionalsutures, treated similarly, developed no zone of inhibition, i.e. themicroorganisms freely grew on and around the conventional suture.

EXAMPLE 6

This example relates to scanning electron microscopy. Scanning electronmicroscope (SEM) images were prepared using sutures that had beenexposed to MRSE in broth culture. Single 6-inch strands of USP size 2-0coated polyglactin 910 suture coated with 0.5% triclosan coatingsolution were placed in separate tubes containing 30 mL of sterile TSBand inoculated with 0.1 mL of a 24-hour culture of the challengeorganism in TSB. Single 6-inch strands of USP size 2-0 Polysorb®(braided lactomer 9-1) suture, available from United States SurgicalCorporation, and which did not contain triclosan, were also prepared inthe same fashion. The tubes were incubated for 24 hours at 37° C. Afterincubation, the sutures were prepared for SEM as follows.

Each strand of the suture was removed from the broth and rinsed byvortexing in 100 mL of sterile saline for 10 seconds. The rinsed strandswere fixed in 10% buffered formalin for 5 minutes. The fixed strandswere dehydrated in ethanol using sequential 5-minute exposures of 50%,70%, 85%, 95%, and 100% ethanol. A final dehydration was performed usinga 5-minute exposure in hexamethylenedisilazane. The samples were airdried prior to SEM. The SEM used for imaging the bacteria was a JEOL(Japan Electronics and Optics Laboratory) JSM-5900LV scanning electronmicroscope.

FIGS. 4 and 5 illustrate the differences between the triclosan-treatedsuture (a) and the untreated suture (b). The triclosan-treated suturehad very few bacteria associated with it anywhere on the surface, whilethe untreated suture was uniformly and heavily coated with bacteria.

The data presented above indicate that coated polyglactin 910 suturewith triclosan exhibits antimicrobial activity in vitro againstStaphylococcus aureus and Staphylococcus epidermidis compared tountreated controls. This activity is evident on a range of suturediameters. The antimicrobial activity endures despite extended exposureto a buffered aqueous environment. Methicillin-resistant strains ofStaphylococcus aureus and Staphylococcus epidermidis were inhibitedafter 24 hours of aqueous extraction by polyglactin 910 with triclosanat low triclosan concentrations. Low levels of triclosan on the sutureare sufficient to greatly reduce colonization of the suture compared tocontrols as illustrated by scanning electron microscopy. These datasupport the conclusion that coated polyglactin 910 suture with triclosanprovides an antimicrobial effect sufficient to prevent in vitrocolonization of the suture by Staphylococcus aureus and Staphylococcusepidermidis.

Moreover, coated medical devices may be stable for extended periods oftime. During storage, coated devices may maintain a sufficient amount oftriclosan to exhibit desired antimicrobial effects. Standard acceleratedaging tests may be used to estimate antimicrobial properties afterexposure to typical storage conditions. Upon exposure to acceleratedaging tests, triclosan coated sutures exhibited zones of inhibitionagainst Staphylococcus aureus and Staphylococcus epidermidis. Inparticular, triclosan coated sutures were exposed to 50° C. for 157days. Table 6 indicates triclosan loss from various USP size 2-0 coateddyed polyglactin 910 sutures with varying levels of triclosan uponexposure of the sutures to 50° C. for 157 days. The exposure took placeafter the sutures had been ethylene oxide sterilized and placed in a hotroom for three days. Table 7 exhibits antimicrobial properties of thosesutures after such exposure. As indicated in Table 7, zones ofinhibition were exhibited against both Staphyloccocus aureus andStaphylococcus epidermidis after exposure. Although no zones ofinhibition were exhibited against Streptococcus agalacticae under thesetesting conditions, higher concentrations of triclosan are known toinhibit growth of Streptococcus agalacticae. It is important to notethat standard accelerated aging tests do not employ true hospitalstorage conditions, and thus, typically demonstrate worst-casescenarios. As such, the stability of triclosan coated sutures isbelieved to be significantly longer under normal shelf-storageconditions.

TABLE 6 Triclosan Loss at 50° C. for 2-0 Dyed Vicryl Suture afterEthylene Oxide Sterilization and 3 Days in Hot Room 1% Solution 2%Solution 3% Solution at 50° C. Irgacare at 50° C. Irgacare at 50° C.Irgacare Days ppm Days ppm Days ppm 0 200 0 295 0 333 3 127 3 216 3 2663 132 3 235 3 291 3 156 3 230 3 291 11 94 11 163 11 227 11 91 11 163 11213 18 89 18 140 18 189 32 69 32 120 32 155 58 58 58 108 58 164 157 59157 118 157 130 157 39 157 79 157 101

TABLE 7 Zones of Inhibition for 2-0 Dyed Vicryl Suture after Exposure to50° C. for 157 Days Triclosan Triclosan Zone of Inhibition (Yes/No)Coating Conc. on Suture Storage Conditions/ S. aureus Strep agalacticaeS. epidermidis (%) (ppm) Sterilization Cycle 24 hr. 48 hr. 24 hr. 48 hr.24 hr. 48 hr. No No No No No No 1.0 39 50 C. for 157 days/ Yes No No NoYes Yes N cycle 2.0 79 50 C. for 157 days/ Yes Yes No No Yes Yes N cycle3.0 101 50 C. for 157 days/ Yes Yes No No Yes Yes N cycle 1.0 59 50 C.for 157 days/ Yes No No No Yes Yes N cycle 2.0 118 50 C. for 157 days/Yes Yes No No Yes Yes N cycle 3.0 130 50 C. for 157 days/ Yes Yes No NoYes Yes N cycle

1. A method of making a packaged antimicrobial suture comprising thesteps of: providing a containment compartment that is substantially freeof an antimicrobial agent; positioning a suture within the containmentcompartment, said suture comprising one or more surfaces having anantimicrobial agent disposed thereon, said antimicrobial agent beingselected from the group consisting of halogenated hydroxyl ethers,acyloxydiphenyl ethers, and combinations thereof; placing thecontainment compartment having the suture in an outer package; placingthe outer package, the containment compartment and the suture in achamber; and subjecting the outer package, the containment compartmentand the suture to time, temperature and pressure conditions sufficientto transfer an effective amount of the antimicrobial agent from thesuture to an inner surface of the containment compartment, whileretaining an effective amount of said antimicrobial agent on the suture,thereby substantially inhibiting bacterial colonization on the sutureand the containment compartment.
 2. The method for making a packagedantimicrobial suture according to claim 1, wherein said step ofsubjecting the outer package, the containment compartment and the sutureto conditions sufficient to transfer an effective amount of theantimicrobial agent from the suture to an inner surface of thecontainment compartment, while retaining an effective amount of saidantimicrobial agent on the suture includes an ethylene oxidesterilization process.
 3. The method for making a packaged antimicrobialsuture according to claim 1, wherein the step of subjecting the outerpackage, the containment compartment and the suture to conditionssufficient to transfer an effective amount of the antimicrobial agentfrom the suture to an inner surface of the containment compartment,while retaining an effective amount of said antimicrobial agent on thesuture further comprises the steps of: placing the outer package havingthe containment compartment and the suture therein in a sterilizationunit; heating the sterilization unit to a first temperature; adjustingthe pressure in the sterilization unit to a first pressure value;injecting steam into the sterilization unit to expose the outer package,the containment compartment and the suture to water vapor for a firstperiod of time; adjusting the pressure within the sterilization unit toa second pressure value; introducing a chemical sterilization agent intothe sterilization unit; maintaining the chemical sterilization agent inthe sterilization unit for a second period of time to render asufficient amount of microorganisms within the package non-viable;removing residual moisture and chemical sterilization agent from thesuture; and drying the packaged antimicrobial suture to a desiredmoisture level.
 4. The method for making a packaged antimicrobial sutureaccording to claim 3, wherein the step of introducing a chemicalsterilization agent comprises introducing ethylene oxide gas into thesterilization unit.
 5. A method of making a packaged medical devicecomprising the steps of: providing a package comprising an inner surfacethat is substantially free of an antimicrobial agent; positioning amedical device within the package, said medical device comprising one ormore surfaces having an antimicrobial agent disposed thereon, saidantimicrobial agent being selected from the group consisting ofhalogenated hydroxyl ethers, acyloxydiphenyl ethers, and combinationsthereof; placing the outer package, the containment compartment and thesuture in a chamber; and subjecting the package and the medical deviceto time, temperature and pressure conditions sufficient to transfer aneffective amount of the antimicrobial agent from the medical device tothe inner surface of the package, while retaining an effective amount ofsaid antimicrobial agent on the medical device, thereby substantiallyinhibiting bacterial colonization on the medical device and the innersurface of the package.
 6. The method of claim 1, wherein the suturecomprising one or more surfaces having an antimicrobial agent disposedthereon further comprises at least one active agent selected from thegroup consisting of a biocide, a disinfectant, an antiseptic, anantibiotic, an antimicrobial peptide, a lytic bacteriophage, asurfactant; an adhesion blocker; an oligonucleotide, an efflux pumpinhibitors; a photosensitive dye, an immune modulator and a chelator. 7.The method of claim 5, wherein the medical device comprising one or moresurfaces having an antimicrobial agent disposed thereon furthercomprises at least one active agent selected from the group consistingof a biocide, a disinfectant, an antiseptic, an antibiotic, anantimicrobial peptide, a lytic bacteriophage, a surfactant; an adhesionblocker; an oligonucleotide, an efflux pump inhibitors; a photosensitivedye, an immune modulator and a chelator.
 8. The method according toclaim 5, wherein said step of subjecting the outer package, thecontainment compartment and the suture to conditions sufficient totransfer an effective amount of the antimicrobial agent from the sutureto an inner surface of the containment compartment, while retaining aneffective amount of said antimicrobial agent on the suture includes anethylene oxide sterilization process.
 9. The method according to claim8, wherein the package is subjected to a pressure of less than about 1.0kPa.
 10. A packaged medical device, comprising a sealed package havingan inner surface; and a medical device positioned within said sealedpackage, wherein the inner surface of said sealed package has depositedthereon an antimicrobial agent selected from the group consisting ofhalogenated hydroxyl ethers, acyloxydiphenyl ethers and combinationsthereof, in an amount sufficient to substantially inhibit bacterialcolonization within the sealed package.
 11. The packaged medical deviceaccording to claim 10, further comprising a containment compartment forsaid medical device positioned within said sealed package.
 12. Thepackaged medical device according to claim 11, wherein all of said innersurface, said containment compartment and said medical device havedeposited thereon said antimicrobial agent in amounts sufficient tosubstantially inhibit bacterial colonization thereon.
 13. The packagedmedical device according to claim 10, wherein the antimicrobial agent isdeposited on said inner surface in an amount of at least the minimuminhibitory concentration of said antimicrobial agent for a microorganismof interest.
 14. The packaged medical device according to claim 13,wherein the amount of antimicrobial agent is at least about 5 ppm byweight, based on the weight of the package.
 15. The packaged medicaldevice according to claim 14, wherein the amount of antimicrobial agentis between about 5 ppm and about 5000 ppm by weight, based on the weightof the package.
 16. The packaged medical device according to claim 10,wherein the medical device has said antimicrobial agent depositedthereon in an amount of at least about 30 ppm by weight, based on theweight of the medical device.
 17. The packaged medical device accordingto claim 16, wherein the medical device has said antimicrobial agentdeposited thereon in an amount of between about 30 ppm and about 5000ppm by weight, based on the weight of the medical device.
 18. Thepackaged medical device according to claim 10, wherein the antimicrobialagent is triclosan.
 19. The packaged medical device according to claim10, wherein the medical device comprises an absorbable or non-absorbablematerial.
 20. The packaged medical device according to claim 10, whereinthe medical device is suture material.